1. Technical Field
The present disclosure relates to an imaging sensor, and more particularly, to an imaging sensor capable of detecting a phase difference of focus.
2. Related Art
In a digital photographing apparatus, such as a camera or a camcorder, it is desirable to precisely set focus on an object to capture a clear still image or a clear moving picture. Examples of auto focus (AF) adjusting mechanisms for automatically adjusting focus include a contrast AF and a phase difference AF.
The contrast AF is a mechanism for acquiring contrast values with respect to image signals that are generated by an imaging sensor while position of a focus lens is being changed and moving the focus lens to a position corresponding to the peak contrast value.
The phase difference AF is a mechanism that employs a separate sensing device and detects a focal point based on phase difference of lights applied to the sensing device.
The phase difference AF is generally faster and more precise than the contrast AF. However, the phase difference AF requires a mirror for detecting a focal point, thereby increasing a size of a photographing device employing the phase difference AF. Furthermore, it may be difficult to detect a focal point while images are successively being captured.
Therefore, to resolve the problem, a method of performing phase difference AF without a mirror by arranging phase difference detecting pixels capable of performing phase difference AF at an imaging sensor has been introduced.
However, outputs of phase difference pixels arranged between imaging pixels significantly differ from those of the remaining pixels. Therefore, the phase difference pixels are considered as defective pixels in an output image and causes deterioration of captured images. The same problem may occur even if phase difference detecting pixels are used as imaging pixels.